- Silver Creek Mobile Home Community
- Silver Lake
- Sinclair
- Sioux Center
- Sioux City
- Sioux Rapids
- Sixmile
- Sixteen
- Skunk River
- Sky View Terrace Mobile Home Park
- Skyline Mobile Park
- Skyview Mobile Home Park
- Slater
- Slifer
- Sloan
- Smithland
- Smiths
- Smyrna
- Snefs
- Soldier
- Sollberg
- Solomon
- Solon
- Somber
- Somers
- South Amana
- South Augusta
- South English
- South Garry Owen
- South Ridge Estates